The Lesson
The greatest common factor is the largest factor that is common to two or more numbers.Understanding the Greatest Common Factor
The numbers that multiply together to make another number are its factors. 2 is a factor of 4 because 2 × 2 = 4:


4 ÷ 2 = 2
6 ÷ 2 = 3
What's in a Name?
The Greatest Common Factor (GCF) is so called because it is the largest (greatest) factor that is the same (common) to the numbers. It may sometimes be called:- Greatest Common Divisor (GCD)
- Highest Common Factor (HCF)